Abstract: Effects of film cooling on the internal heat transfer coefficients of turbine blades were investigated numerically and the key factors have been found out as the film cooling hole distance ratio and the inlet Reynolds number.The local heat transfer coefficient variations were discussed both for the pressure and the suction sides of blades.Numerical results showed that,for the pressure side the internal heat transfer coefficient was much enhanced and could be doubled,as compared with the no-hole passages at the same range.Heat transfer coefficient for the suction side,however,was decreased due to film cooling.